1. Field of the Invention
The present invention relates to internal combustion engines and, more particularly, to a carburetor having two control shafts.
2. Prior Art
The present invention relates to fuel injection systems for internal combustion engines and, more specifically, to the control of a low pressure injection in an internal combustion engine. A particular field of application of the invention is a two-stroke internal combustion engine. The specific application described is to a small high speed two-stroke engine, such as utilized in handheld power equipment such as leaf blowers, string trimmers and hedge trimmers, also in wheeled vehicle applications such as mopeds, motorcycles and scooters, and in small outboard boat engines. The small two-stroke engine has many desirable characteristics, that lend themselves to the above applications, including: simplicity of construction, low cost of manufacturing, high power-to-weight ratios, high speed operational capability and, in many parts of the world, ease of maintenance with simple facilities.
The prominent drawback of the simple two-stroke engine is the loss of a portion of the fresh unburned fuel charge from the cylinder during the scavenging process. This leads to poor fuel economy and, more importantly, high emission of unburned hydrocarbon, thus rendering the simple two-stroke engine incapable of compliance with increasingly stringent governmental pollution restrictions. This drawback can be relieved by separating the scavenging of the cylinder, with fresh air, from the charging of the cylinder, with fuel. This separation can be achieved by injecting the liquid fuel into the cylinder or more preferably by injecting the fuel charge by utilizing a pressurized air source, separate from the fresh air scavenge, to spray the fuel into the cylinder. In a preferred embodiment of the present invention, the displacement size of the engine is about 16 cc to about 100 cc, but could be larger or smaller. These sizes of engines are used for such things as string trimmers, chain saws, leaf blowers, and other hand held power tools. The engine could also be used on a tool such as a lawn mower, snow blower or motor boat outboard engine.
In accordance with one embodiment of the present invention, an internal combustion engine is provided having a crankcase, a cylinder connected to the crankcase, a compressed air assisted fuel injection system connected between the crankcase and the cylinder, and a reciprocating piston head located in the cylinder. The improvement comprises a fuel delivery system having two carburetor sections with two interconnected rotatable shafts.
In accordance with another embodiment of the present invention, an internal combustion engine carburetion system is provided comprising a frame having two air flow channels; two throttle shaft assemblies connected to the frame and extending into respective ones of the air flow channels; and a movement system for moving the two throttle shaft assemblies.
In accordance with one method of the present invention, a method of assembling a carburetor for an internal combustion engine is provided comprising steps of providing a frame having two air flow channels through the frame, the frame having a fuel conduit system for supplying fuel to the two air flow channels; connecting two control shaft assemblies to the frame, a first one of the shaft assemblies extending into a first one of the air flow channels; and operably connecting the two control shaft assemblies to each other to coordinate movement of a second one of the shaft assemblies at least partially relative to movement of the first shaft assembly. Movement of the second shaft assembly at least partially controls supply of fuel delivery to a second one of the air flow channels, and wherein movement of the first shaft assembly from a first idle position to a second wide open throttle position has a coordinated movement of the second shaft assembly from a first small or no fuel supply delivery position to the second air flow channel to a second relatively larger fuel supply delivery position with fuel delivery being switched, at least partially, from the first air flow channel to the second air flow channel when the two control shafts are moved between their respective first and second positions.